refactor: simplify logo to clean doorway arch with amber light

Remove glow ring, widen arch proportions, and center light element.
Three clean elements: arch, threshold, amber circle.

src/fastapi_oidc_op/static/logo.svg

@@ -1,14 +1,8 @@
 <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 64 64" fill="none">
-  <!-- Light / glow circle -->
-  <circle cx="32" cy="12" r="5" fill="#d97706"/>
-  <!-- Subtle rays -->
-  <line x1="32" y1="3" x2="32" y2="5" stroke="#d97706" stroke-width="2" stroke-linecap="round"/>
-  <line x1="23.5" y1="5.5" x2="25" y2="7" stroke="#d97706" stroke-width="2" stroke-linecap="round"/>
-  <line x1="40.5" y1="5.5" x2="39" y2="7" stroke="#d97706" stroke-width="2" stroke-linecap="round"/>
-  <line x1="21" y1="12" x2="23" y2="12" stroke="#d97706" stroke-width="2" stroke-linecap="round"/>
-  <line x1="43" y1="12" x2="41" y2="12" stroke="#d97706" stroke-width="2" stroke-linecap="round"/>
   <!-- Doorway arch -->
-  <path d="M16 62 V32 A16 16 0 0 1 48 32 V62" stroke="currentColor" stroke-width="3.5" stroke-linecap="round" stroke-linejoin="round" fill="none"/>
+  <path d="M15 56 V28 Q15 10 32 10 Q49 10 49 28 V56" stroke="currentColor" stroke-width="4" stroke-linecap="round" stroke-linejoin="round" fill="none"/>
-  <!-- Threshold line -->
+  <!-- Threshold -->
-  <line x1="14" y1="62" x2="50" y2="62" stroke="currentColor" stroke-width="3.5" stroke-linecap="round"/>
+  <line x1="11" y1="56" x2="53" y2="56" stroke="currentColor" stroke-width="4" stroke-linecap="round"/>
+  <!-- Light -->
+  <circle cx="32" cy="26" r="6" fill="#d97706"/>
 </svg>